See Acuva at the 2019 IUVA World Congress

The 2019 IUVA World Congress will bring together well known academic and industrial experts from all over the world to discuss novel developments and practical applications of UV technologies on February 10-13, 2019 in Sydney, Australia. Learn more: www.iuva.org/2019-World-Congress

The conference program will feature three days of presentations including new findings in the development of UV-LEDs. Acuva’s very own Dr. Ashkan Babaie and Dr. Babak Adeli are set to make the following technical presentations during the conference:

UV-C LEDs: Datasheet vs. Reality

Ultraviolet (UV) radiation is known as the most effective water disinfection route. However, utilization of conventional UV-lamp can be limited for point-of-use (PoU) disinfection applications, due to their high energy consumption, frequent maintenance, warm-up time. Water disinfection systems based on germicidal ultraviolet light emitting diodes (UV-C LEDs) is emerged as an alternative UV source, offering enormous potentials for design and manufacturing of highly efficient PoU disinfection devices.

Despite its numerous advantages, commercial UV-C LEDs emerged in the last decade; thus, their characteristics and reliability are not well-documented. Uncertainties on the key characteristics of commercial UV-C LEDs, against those reported in manufacturer’s datasheet, such as total radiant flux, emission spectrum, radiation pattern, thermal stability, heat dissipation, and lone-term performance have incurred challenges on UV-LED water disinfection system designers and developers.

Here, we present a comprehensive study on optical, electrical and thermal characterization of UV-C LEDs. In addition, the importance of UV-C LEDs characteristics corresponding to the microbial performance of LED-based water disinfection application will be evaluated, and a guideline will be proposed to examine the reliability of UV-C LEDs through highly accelerated life test (HALT). The presented data will be compared to those provided in manufacturers datasheet, and the discrepancies will be elaborated. Finally, an insight on the reliability of UV-C LEDs, with focus on water disinfection application, will be proposed.

Simulation Techniques for High Precision UV Dose Estimation in UV-LED Water Purification Systems

Using virtual prototyping for the design of UV-LED reactors is significantly beneficial in reducing the product development cost. Without the proper simulation tools, the reactor design may need to go through multiple design revisions and prototyping stages without delivering the required UV dose or LRV at the end. Complete simulation of a reactor’s performance requires precise modelling of reactor’s hydrodynamics, optics and the microbial kinetics, each of which are equally important for an accurate reactor simulation.

Hydrodynamic simulation can be quite challenging if not all the parameters are considered or set properly. Meshing quality, flow models including turbulence, particle tracking setting can all significantly affect the flow simulation and the dose performance, respectively. In fact, through examples, it will be discussed that traditional measures of simulation convergence as having the residuals below a certain level will not necessarily verify the accuracy of simulation. In addition, optical simulation will equally be important to achieve an accurate prediction of the reactor’s performance. Precise simulation of the LED die, package, radiation pattern and wavelength, as well as modelling of optical surfaces will all influence the accuracy of the simulation tool.

In this study, a step-by-step approach for both optical and flow simulation within a UV-LED based water purifier will be discussed using commercial software packages such as Ansys and Zemax. Once reliable optical and hydrodynamic data are available, it will be explained how an integrated tool can be used to determine the overall reactor’s UV dose delivery. Using the same approach, the simulation results will be compared with experimental bioassay test results, showing less than 10% variation. This level of accuracy can be achieved between experiments and simulation by paying extra attention to the detail of hydrodynamics, optics and kinetics simulation tool.

The Journey Towards the First NSF 55 Certified UV-LED Water Purifier

Acuva’s Eco 1.5 recently became the first UV-LED water purifier to be certified against NSF 55-Class B by The International Association of Plumbing and Mechanical Officials (IAPMO). As the primary standard for ultraviolet microbiological water treatment systems, NSF 55 verifies claims regarding disinfection capability of water treatment devices. In addition, the scope of this standard includes material safety and structural integrity of the water purifier. As part of the certification process, the production facility is audited to evaluate the quality control process within the production facility.

The NSF 55 certification process is indeed a very valuable and demanding exercise to assure the effectiveness and safety of the water treatment system for microbial disinfection, with respect to the fact that currently no other standard is available specific to UV-LED water treatment devices; however, considering NSF 55 has primarily been developed based on the utilization of UV mercury lamps in water disinfection systems, there are challenges involved in following the standard protocols for UV-LED based water purification systems.

In this presentation, the certification process of Acuva’s Eco 1.5 against NSF 55 with IAPMO will be explained, including the detail of the bioassay, material extraction and pressure tests along with the official test results. In addition, the overall NSF 55- Class B standard will be evaluated in respect to UV-LED based water treatment systems. We will share our learnings within the certification process and offer an insight on improving the current protocols or establishing an alternative approach for global validation of UV-LED water disinfection systems for different industries and markets.

The Impact of Inorganics on the Performance of UV Water Treatment Systems

Inorganic minerals in water are classified into ‘healthy’ and ‘unhealthy’ compounds. Primary water treatment technologies, such as membranes and advanced filtration, has placed an emphasis on the elimination of unhealthy minerals such as lead, arsenic, and antimony; while preserving those benefit human health, such as calcium, magnesium and potassium. In particular, calcium and magnesium are the most common minerals in water supply, and their concentration is recognized as the water hardness indicator.

Despite their health benefits, minerals tend to deposit inside disinfection systems, particularly, in the vicinity of conventional UV lamps, owing to their temperature dependent solubility in water. In addition, hard water exhibits lower UV transmittance (UVT), compared to water with less than 120 ppm minerals content, the so called ‘moderately hard’ water. Therefore, the disinfection performance of UV water treatment system is a strong factor of water hardness level, and the application of UV-based water disinfection systems is limited in the regions with high mineral content in water supply.

Here, we will discuss the effect of water hardness level on the performance and reliability of UV disinfection products. UV-LED and UV-lamp disinfection systems were operated with ‘hard’ and ‘extremely hard’ water, and their optical characteristics were evaluated. Furthermore, the effect of mineral content on water UVT, and subsequently the microbial disinfection performance of UV systems was correlated and guidelines for operation of UV systems for regions with high mineral content water will be presented. It is shown that UV-LED disinfection systems exhibit consistent microbial disinfection, owing to uniform temperature gradient across the reactor. The outcome of this study provides an insight on reliable operation of UV disinfection systems in regions with various water qualities.